Boost issues-Stuck BOV?

[ksd9000]

Hello all. Just got done rebuilding the engine and running into some issues. All components are stock except for the 3" turbo back exhaust. No CAT and just a free flow muffler at the end.

The issue I am having is that the intake soft pipe (where it comes out of the right fender well to the 3000 pipe) keeps blowing off when I push it hard. Stock boost gauge shows 8+ psi when this happens. Double checked all vacuum lines and made sure the bypass valve is connected. Looked through the TSRM and didnt see any info on how to test it. It also sounds like there is no pressure relief when I let off the gas after hard acceleration. I can hear the intake charge resonating in the intake after the hard acceleration and let off the pedal.

Maybe I'm not tightening the intake tubes enough, but I dont want to chance it and not have ANY pressure relief if the BOV is not working correctly.

Car is not being driven for street use. Track only. Not that it makes a difference.

Any help is appreciated.....

[cre]

Yup, sounds like the BOV is to blame.... that and a dried out or dirty IC coupler. Use a vacuum pump on the BOV's signal line to test the valve. If this is an aftermarket BOV refer to the manual to see if there's a trigger adjustment.

[ksd9000]

Its the stock bypass valve. And the IC rubber piping is surprisingly still soft and pliable. Plus I cleaned all the piping out thoroughly before reassembly.

Applying vacuum at idle should make the valve open and cause the engine to stumble correct?

[cre]

Originally Posted by ksd9000

Its the stock bypass valve. And the IC rubber piping is surprisingly still soft and pliable. Plus I cleaned all the piping out thoroughly before reassembly.

Pliable or not it shouldn't even be coming off at 14+psi. Something's wrong with it, the clamp or your arm strength.

Originally Posted by ksd9000

Applying vacuum at idle should make the valve open and cause the engine to stumble correct?

No. the valve dumps back into the intake AFTER the KVAFM, so the air is metered and accounted for.

[ksd9000]

Thanks for all the help CRE.

Did some more testing and found that the BSV is not closing. Relieving pressure all the time. I have been looking into the Saab BSV P/N 0 280 142 110 as an alternative. Any suggestions on where I can get one without getting robbed? I'm leery of going used because the used one may have the same issue as the one I have now.

I'm tired of messing with this thing. I have a race in 3 weeks and this is driving me nuts!

[cre]

I wouldn't run a used unit either. Did you apply pressure to the BPV's trigger/signal line before drawing the conclusion it isn't closing?

The Bosch BPVs are decent units. There are two commonly used, the less expensive one will handle about 9 or 10 psi on a regular basis and the more expensive one will handle 14 - 16psi regularly without failure. I don't have the part numbers handy. Both are used by Saab.



Can't even get the IC piping to stay together and you're already setting race dates... and .... Supra owner through and through.